摘要：The importance of effective measurement of process measurands in offshore oil and gas processing facilities cannot be over emphasized. Due to environmental influences, aging, vibration, wear and tear, etc over-time, these measurement systems experience drifts, giving misleading information about the process variables. In this study it was desired to evaluate the drift in 3 pressure Gauges at an offshore platform. Periodic inspections were performed on the Gauges over a 6-month period. Results showed zero and minor drifts in the measurands after 1-month and 3-monthsusage, respectively. However, after 6-months usage, significant drifts were recorded, corroborating the rule-of-thumb for pressure measurands. The drift models were linear with R2= 1.0 for measurand less than 6 months of instrument usage, and R2< 1.0 for usage periods ≥ 6 months. Recalibration results showed instability for input pressures ≥50% gauge range, and hence faster convergance for input pressures ≤ 50% of gauge range. Validation results showed variance and standard deviation 3685Psi (25.407MPa)and 60.7Psi (0.418MPa), respectively for Gauge 3 at 4000 Psi (27.579MPa)input pressure. To restore the Gauges, recalibrations by error convergence and validations by replications were performed.
